1. Field of the Invention
The present invention relates to a susceptor with a built-in electrode and a manufacturing method therefor, and relates specifically to a susceptor with a built-in electrode which has high corrosion resistance and plasma resistance, and in which leakage current can be prevented, and a manufacturing method for a susceptor with a built-in electrode whereby a susceptor with a built-in electrode can be manufactured economically, with a high yield rate.
2. Description of the Related Art
Recently, beginning with manufacturing methods for semiconductor devices such as IC, LSI and VLSI, a move towards single substrate processing is proceeding in the manufacturing method for display devices such as liquid crystal displays (LCD) and plasma displays (PDP), and in the assembly process for hybrid ICs, in which plate specimens such as semiconductor wafers, liquid crystal glass substrates, printed circuits, etc. are processed individually, so that an etching process or a deposition process can be performed evenly on each individual wafer or substrate.
In this single substrate processing, in order to keep the plate specimens separate in the processing room, the plate specimens are mounted on a stage (seat) called a susceptor, and the prescribed processing is performed.
Because this susceptor must withstand use within plasma and use at high temperatures, the susceptor must have excellent plasma resistance and high heat conductivity.
For such a susceptor, a susceptor formed from an aluminum nitride based sintered body, which has excellent plasma resistance and heat conductivity is used.
One class of such a susceptor is a susceptor with a built-in electrode, in which an internal electrode such as; an electrostatic chuck electrode which generates an electric charge and secures the plate specimen by electrostatic attraction, a heater electrode which heats the plate specimen by current heating, a plasma generation electrode for performing plasma processing by conducting high frequency power to generate plasma, or the like, is provided inside of the susceptor substrate which has a mounting surface for mounting the plate specimen.
FIG. 5 is a cross-sectional view showing an example of a conventional susceptor with a built-in electrode formed from an aluminum nitride based sintered body. This susceptor 1 comprises; a mounting plate 2 for mounting the plate specimen, a support plate 3 which supports this mounting plate 2, an internal electrode 4 which joins and integrates the mounting plate 2 and the support plate 3 and which is formed from a conductive binder layer, and power supply terminals 5 which are embedded in the support plate 3 so as to contact this internal electrode 4, and which supply electrical current into the internal electrode 4.
The mounting plate 2 comprises a plate shaped body formed from a nonconductive and dielectric aluminum nitride sintered body, the support plate 3 comprises a plate shaped body formed from a nonconductive aluminum nitride based sintered body, and the conductive binder layer which forms the internal electrode 4 is made from either an organic compound or a metal.
This susceptor with a built-in electrode 1 has a problem in that, as described above, since the mounting plate 2 and the support plate 3 are joined by a conductive binder layer made from a different material, that is by the internal electrode 4, the join between the mounting plate 2 and the support plate 3 can easily become inadequate, so that there is a possibility of the internal electrode 4 being exposed to gas or plasma if the interface is penetrated by corrosive gas or plasma, or that the joint interface of the mounting plate 2 and the support plate 3 may be damaged, and hence the corrosion resistance and plasma resistance is insufficient for use as a susceptor.
In this conventional susceptor with a built-in electrode 1, it is necessary to prevent the penetration of gas and plasma into the joint by ensuring a sound join between the mounting plate 2 and the support plate 3.
FIG. 6 is an exploded cross-sectional view showing each structural element of an improved susceptor with a built-in electrode 11 which improves on these points, and FIG. 7 is a cross-sectional view showing the entire form of this improved susceptor with a built-in electrode 11. The construction is such that a ring shaped flange 12a is provided around the peripheral edge of the lower surface of the mounting plate 12 which is formed from an aluminum nitride based sintered body, and a circular depression 12b is thus formed in the bottom surface of the mounting plate 12.
Then, by integrating into this depression 12b an internal electrode 13 formed from a conductive binder layer, and a support plate 15 which is formed from an aluminum nitride based sintered body into which a power supply terminal 14 is embedded, the improved susceptor with a built-in electrode 11 is obtained.
However, the susceptor with a built-in electrode 11 as described above has a problem in that the mounting plate 12 must be processed so as to have the shape described above, and the internal electrode 13 and the support plate 15 must be designed to fit within the depression 12b in the mounting plate 12 without any gaps. Consequently the manufacturing method for this susceptor with a built-in electrode 11 is complex, and the manufacturing costs are high.
Furthermore, these susceptors with built-in electrodes 1 and 11 have in common a problem in that the nonconductivity thereof reduces under high temperatures, for example, the volume resistivity value under a temperature of 300° C. is approximately 106Ω/cm, and leakage current occurs.